[Facial asymmetry after vascular pedicled muscle transfer. Additional criterion for evaluating outcome in managing chronic facial paralysis].

Today neurotization and muscle transplantation are considered an ideal method of reconstructing the function of the facial nerve and the mimetic muscles in long-established facial palsy. Transplantation of the gracilis muscle as a segmental muscle provides an appropriate size for the face; however, determining the amount of muscle is difficult in order to obtain the desired dynamic and symmetric results. Prompted by the question of an "ideal" transplant size, a retrospective study was undertaken. Since 1991, 11 microneurovascular gracilis muscle transfers have been performed in 10 patients with long-established facial palsy (one patient underwent an additional transfer due to excessive scarring in a severe case of neurofibromatosis). Computed axial tomography scans were performed on six patients using a method for obtaining muscle-volume measurements of corresponding areas in each individual by using bony landmarks for reference. Cross-section area measurements by a digitalized mode were obtained from each scan, determining 20-70 Hounsfield units as appropriate for muscle tissue. Muscle-volume measurements ranged on the transplantation sites between 3.85 and 62 cm3 compared to 1.4 and 22.3 mm3 for the corresponding sites. The increments in muscular tissue by a factor between 2 and 3 are due to an increase in each single scan of the corresponding sides: when comparing the corresponding operated and unoperated sides in each patient, soft-tissue volumes were significantly (P < 0.005) elevated on the operated side. The findings presented in this study demonstrate not only encouraging functional results, but also show significant improvement of facial symmetry at rest. The results of our investigation support those of other authors, who also saw the main difficulty as determining the appropriate graft size. Secondary corrective procedures of the muscle puts the pedicle at risk of vascular and neural damage. Meticulous shaping of the graft and proper fixation and suspension technique cannot be overemphasized.